Process of combining gases by contact process.



UNITED STATES PATENT FFICE.

MAX SOHROEDER, OF HAMBORN, GERMANY, ASSIGNOR OF TWVO-THIRDS TO THEAOTIEN-GESELLSOHAFT FUR ZINK-INDUSTRIE, VORMALS WILHELM GRILLO, OFOBERHAUSEN, GERMANY, AND AUGUST HECKSOHER, OF NEW YORK, N. Y.

PROCESS OF COMBINING GASES BY CONTACT PROCESS.

SPECIFICATION forming part of Letters Patent N 0. 636,924, datedNovember 14, 1899. Application filed October 19, 1898. Serial No.694,019. (No specimens.)

To all whom it may concern.-

Be it known that I, MAX SOHROEDER, a German subject, residing atHamborn, Rheinland, Germany, have invented certain new and usefulImprovements in the Recovery of Sulfuric Acid and Sulfuric Anhydride;and

I do hereby declare the following to be a full, clear, and exactdescription of the invention, such as will enable others skilled in theart to [0 which it appertains to make and use the same.

The present invention relates to the art of recovering sulfuric acid orsulfuric anhydride (80,) by the catalytic or contact method, wherein, asis well known, platinum has shown itself as an especially effectivesubstance over all others for producing the desired result.

Inasmuch as platinum, even in finely-divided condition, is of too smallvolume to act eifectively throughout in a large current of gasescontaining sulfurous anhydride (S0 and oxygen, resort was soon had tothe expedient of superimposing the metal upon an inert or comparativelyinert base, so as to spread the metal out over a large surface.Pumice-stone was at first proposed for this purpose and appearedespecially applicable thereto on account of its numerous cavities.Winkler developed the subject further and 0 ascertained that almost allloosely porous bodies are adapted to serve for the contact substanceproper, especially asbestos, and also mineral wool, infusorial earth,clay, and (in so far as in certain contact processes no high temperatureis required) even organic fibrous materials. In German Patent N 0. 4,566Winkler describes a special process for the chemical application ofplatinum upon these bases, which process he likens to the final step inthe dyeing of a fiber in the dyevat. Moreover, from later publicationsit appears that for the production of these platinized contact bodiesthere has always been employed a base either molded to shape orotherwise in integral or solid condition.

The present invention contemplates the subdivision or dilution of theplatinum in a different manner and by other means,whereby in a verysimple way contact masses of extraordinary subdivision maybe obtained,which far exceed in efficiency those heretofore employed.

Instead of the solid or integral bases hereinbefore referred toemployment is made of the soluble salts of the alkalies, of the alkalineearths, of the earths, and of the metals, which salts, for theproduction of the contact mass, are to be dissolved in Water and thenmixed with a solution of the finely-divided platinum salt. The mixtureof the so lutions is then to be evaporated and the resulting salt crustsdried and broken up to about a uniform granular size. The powder whichis formed during this reducing or breaking-up operation is to bedissolved anew in water and treated as before until all of the materialhas been converted into an 'appropriate condition of grains orparticles. This material is adapted directly for filling the cylindersor other apparatus employed in carrying out the contact process. Theseparation of the metallic platinum in the finest subdivision betweenthe molecules of the salts serving as vehicles for the platinum takesplace of itself upon heatingi. 6., upon the starting of the contactprocess.

It will be apparent that the salts serving as vehicles for thefinely-divided platinum will only remain unchanged during the contactprocess provided they are either stable sulfates or provided theycontain an acid which-as, for instance, phosphoric acidis stronger at alow red heat than the sulfuric acid which forms during the process.Other saltsas, for instance, chlorids or carbonates-will at thebeginning of the process be at once converted into sulfates with development of their acids. Inasmuch as this results for the most part in analteration of the structure and injury to the firm cohesion of theindividual'pieces, it is advisable to employ stable salts from thebeginning.

As an example of particular proportions for obtaining a contact massinvolving my invention, but without in any way intending to limit myselfthereto, I may state that in some ,layers, which diminish theirefficiency.

instances the contact mass may be produced by dissolving in the smallestquantity of water one hundred pounds of sulfate of potassium, onehundred pounds of sulfate of magnesium, and one hundred pounds ofsulfate of aluminium and adding to the solution ten pounds of chlorid ofplatinum, likewise dissolved in water, whereupon the mixture isevaporated, dried, and granulated, as described.

It will be understood that instead of the single salts mixtures thereofor double saltsas, for instance, alum-can be employed. Furthermore,instead of platinum other metals of the platinum group may be used,which, however, in view of their great rarity, come less intoconsideration in practice.

The technological advantages of this new contact material consist notonly in the simple manner of producing it, but also in its highlysuperior efficiency. The platinum finds itself in a condition ofextraordinarilyfine subdivision and appears to be effective in theinterior. of the pieces to a degree not less than in the exteriorlayers. This may be due to the great porosity produced by the drivingoff of the water of crystallization. The solubility of the salts withinwhich the catalytic agent is occluded in contact bodies made inaccordance with my invention is particularly of value when the ordinaryfurnacegases from sulfur ores are employed for the contact process.Inasmuch as the furnacegases even after purifying still contain tracesof dust, the contact bodies in the course of time become covered withthick impenetrable To lay bare the surface, it is only then necessary tostir the contact body in water and to evaporate the salt solution thusformed. The dust is thereby dispersed throughout the entire mass and canno longer diminish the penetrability of the surface. Finally, the dustmay be readily separated from the platinum after dissolving out thesalts which serve as the vehicle. For this purpose it is only necessaryto boil with concentrated muriatic acid the slime which has beenseparated from the salt solution, whereupon the particles of dust passinto solution while the platinum-black remains behind in a purecondition.

Having thus described the invention, what I claim is- 1. The process ofrecovering sulfuric acid or sulfuric anhydride from gases containing S0and O, which consists in passing said gases through a mass comprising acatalytic agent and soluble salts, substantially as described.

2. The process of effecting the chemical union of gases by catalysis,from a mixture of said gases together with accompanying impurities, andsubsequently releasing the cata lytic agent from its carrier or vehicle,which consists in passing said gases through a contact mass containing acatalytic agent and one or more soluble salts serving as a carrier orvehicle therefor, until the eificiency of the mass has become impairedby the action of the impurities thereon, and then dissolving out thesaid soluble carrier salts, thereby releasing the catalytic agent;substantially as described.

3. The process of effecting the chemical union of gases, by catalysis,from a mixture of said gases together with accompanying impurities, andsubsequently releasing the catalytic agent from its carrier or vehicleand recovering it, which consists in passing said gases through acontact mass containing a catalytic agent and one or more soluble saltsserving as a carrier or vehicle therefor, until the efficiency of themass has become impaired by the action of the impurities thereon, thendissolving out the said soluble carrier salts, thereby releasing thecatalytic agent, separating it from the solution, and then removing fromit the impurities; substantially as described.

4. The process of producing a material suitable for use in catalysis,which consists in making a mixture containing a liquid, aplatinum saltand one or more suitable soluble salts, evaporating the mixture andobtaining salt crusts therefrom, and reducing the platinum salt in themass to the metallic state so as to leave it occluded therein in a stateof fine subdivision; substantially as described.

5. The process of producinga material suitable for use in catalysis,which consists in making a mixture containing a liquid, a catalyticagent, and one or more suitable soluble salts, evaporating the mixtureand obtaining salt crusts therefrom, wherein the said soluble saltsserve as soluble carriers or vehicles for the catalytic agent,substantially as described.

In testimony whereof I aifix my signature in presence of two witnesses.

MAX SCHROEDER.

